Dyeing cellulosic textiles with vat and sulfur dyes using sodium dithionite and an aldehyde-bisulfite addition product stabilizer

ABSTRACT

An improved process for dyeing cellulosic textiles with vat or sulfur dyes using sodium dithionite as reducing agent, using as a stabilizer for the reducing agent a stabilizer of the formula WHEREIN M is a monovalent cation selected from the class consisting of alkali metal and ammonium cations, R is a monovalent group selected from the class consisting of hydrogen, alkyl, alkenyl and furyl, n is an integer of 1 to 3, X is a group having a valence of n and is selected from the class consisting of hydroxyl and substituents having the formula R&#39;&#39;3 n N and R&#39;&#39; is a monovalent radical selected from the class consisting of hydrogen and monovalent hydrocarbon, said stabilizer being used in an amount providing about 0.01 to about 2 mols of UNIT OF SAID STABILIZER PER MOL OF SAID REDUCING AGENT. Also, the stabilizer as defined above in dry particulate form and novel mixtures of reducing agent and stabilizer.

United States Patent Etters [54] DYEING CELLULOSIC TEXTILES WITH VAT AND SULFUR DYES USING SODIUM DITHIONITE AND AN ALDEHYDE-BISULFITE ADDITION PRODUCT STABILIZER [72] Inventor: James N. Etters, Danville, Va.

[73] Assignee: Dan River Inc., Danville, Va.

[22] Filed: May 26, 1969 [21] Appl.N0.: 827,894

[52] US. Cl ..8/34, 8/79, 8/37,

I 260/3472, 260/503 511 int. Cl ..D06p 1/22, D06p 1/30 58 FieldotSearch ..s/34,37

[56] References Cited UNITED STATES PATENTS 5/1930 Thompson, Jr. ....8/34

OTHER PUBLICATIONS Fox, Vat Dyes & Dyeing, 1947, p. 38 Grant, Hackh s Chem. Dic., 1969, p. 223 & 335

Primary Examiner-George F. Lesmes Assistant Examiner-Patricia C. Ives Attorney-Christen & Sabol [5 7] ABSTRACT An improved process for dyeing cellulosic textiles with vat or sulfur dyes using sodium dithionite as reducing agent,

[ 1 Feb.29, 1972 using as a stabilizer for the reducing agent a stabilizer of the formula wherein M is a monovalent cation selected from the class and R is a monovalent radical selected from the class consisting of hydrogen and monovalent hydrocarbon, said stabilizer being used in anarnount providing about 0. 0 1 to about 2 mols of unit of said stabilizer per mol of said reducing agent. Also. the stabilizer as defined above in dry particulate form and novel mixtures of reducing agent and stabilizer.

4 Claims, No Drawings IWILING CELLULOSIC TEXTILES WITH VAT AND SULFUR DYEH USING SODIUM DITHIONITE AND AN ALDEHYDE-BISULFITE ADDITION PRODUCT STABILIZER BACKGROUND OF THE INVENTION 1. Field Of The Invention The present invention relates to an improved process for dyeing cellulosic textiles with vat or sulfur dyes using sodium dithionite as a reducing agent and using a novel stabilizer comprising the addition products of an organic aldehyde and sodiurn bisulfite with or without ammonium or a suitable organic primary or secondary amine. The invention also relates to novel mixtures of sodium dithionite and such stabilizers, preferably as a dry mixture and also relates to the stabilizer in dry particulate form which is easy to handle, ship, and/or store.

2. Description Of The Prior Art Sodium dithionite has long been used and is still being used quite extensively in the dyeing of cellulosic textiles with vat or sulfur dyestuffs. It has been a considerable problem to prevent oxidative decomposition of sodium dithionite during the dyeing process. Sodium dithionite is such an efficient reducing agent that mere exposure to air at moderate temperatures will bring about its oxidative decomposition.

Attempts have been made to overcome this problem. As early as 1911 it had been proposed to add acetaldehyde to the dyebath containing sodium dithionite during vat and indigo printing. In 1921 there was offered for sale sodium acetaldehyde sulfoxylate which decomposed with heat to liberate active reducing agent. The addition of acetaldehyde to the dyebath in itself posed problems. Because of its high volatility acetaldehyde which boils at room temperatures was lost to the atmosphere and thus not only created a health hazard but was wasteful. The sodium acetaldehyde sulfoxylate product mentioned above was expensive and more difficult to manufacture in a form convenient for textile uses.

In addition, sodium dithionite had been used in conjunction with sulfinic acid derivatives as described in U.S. Pat. No. 3,265,459 and British Pat. Nos. 837,940 and 829,177. Such derivatives are expensive and difficult to make in a form advantageous for use in the dyebath.

SUMMARY OF THE INVENTION The present invention provides an improved dyeing process using vat or sulfur dyestuffs and sodium dithionite as a reducing agent and using novel stabilizers for the reducing agent. The stabilizers used in this invention are essentially nonvolatile as compared to the aldehydes, such as acetaldehyde and thus have little or no problems from a health or air pollution standpoint. Moreover, the stabilizers used herein .can be produced in solid powder form, thus offering considerable packaging, shipping, and handling advantages and can be mixed in such dry particulate form with dry sodium dithionite wherein M is a monovalent cation selected from the class consisting of alkali metal and ammonium cations, R is a monovalent group selected from the class consisting of hydrogen, alkyl preferably having one to four carbon atoms, alkenyl preferably having one to four carbon atoms, and fury], n is an integer of l to 3, X is a group having a valence of n and is selected from the class consisting of hydroxyl and substituents having the formula and R is a monovalent radical selected from the class consisting of hydrogen and monovalent hydrocarbon having one to 18, preferably one to six, carbon atoms and preferably alkyl, said stabilizer being used in an amount providing about 0.0] to about 2 mol of R -lH s 6 h unit of said stabilizer per mol of said reducing agent.

These addition products are very easily prepared by mixing the aldehyde and the bisulfite in an aqueous mixture at room temperatures or elevated temperatures if desired. The addition products are formed by the reaction of l mol of the aldehyde and l mol of the bisulfite; therefore, the aldehyde and bisulfite need only be mixed in equimolar proportion. However, if desired, other than equimolar proportions can be employed. If it is desired to produce a dry, particulate stabilizer, the aqueous reaction solution is simply dehydrated, thus providing a dry powdery, flake or granular form of the addition product.

Suitable aldehydes which can be employed in the production of these addition products include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, furfuralIdehyde], acrolein and any other suitable aldehydes. The alkyl aldehydes, preferably those having one to four carbon atoms and furfuralldehyde] are preferred. Illustrative bisulfite reactants useful in the production of the addition products include sodium bisulfite, potassium bisulfite, other alkali metal bisulfites and ammonium bisulfite.

Listed below are several reaction equations which illustrate the reaction taking place during the production of the addition products.

The addition products thus produced can be portrayed by formula I wherein X is hydroxyl.

lfdcttired, ammonia or a primary or secondary nminc having izer as defined by the formula I wherein X is a substituent having the formula wherein in both instances R and n are as defined above. When ammonia is condensed with the aldehyde-bisulfite addition product, the resulting addition product can be portrayed by formula I wherein X is nitrogen and n is 3. When a primary amine is used, the resulting product can be portrayed by formula I wherein X has the formula R'N and n is 2. When a secondary amine is used, the resulting addition product can be portrayed by formula I wherein X is R' N- and n is 1.

Any suitable primary amine can be used including methylamine, ethylamine, propylamine, aniline, toluidine, benzylamine and the like. Any suitable secondary amine can be used, e.g., dimethylamine, diethylamine and methylaniline. After further addition of ammonia or amine, the resulting addition product can also be dehydrated to form a powdery, flake or granular stabilizer.

The condensation of the aldehyde-bisulfite addition product with ammonia or the primary or secondary amine can be typified by the following reaction equation:

The addition products, with or without condensation with ammonia or amine can be added to the dyebath at any desired stage of dyeing. It is, however, preferred to add the addition product at or about the same time that the sodium dithionite is added so as to preclude as much as possible oxidative decomposition of the sodium dithionite before contact with the stabilizer. In those instances where the dyebath does not come into contact with oxygen or the atmosphere until a certain stage in the dyeing process, the stabilizer need not be contacted with the sodium dithionite until there is a risk of contact with oxygen. Thus, the stabilizer need only be contacted with the sodium dithionite at or about the time the sodium dithionite is likely to come into contact with oxygen or air. In most cases, it is desirable to add the reducing agent and stabilizer at about the same time to avoid the risk of undesired oxidative decomposition.

It is also convenient to mix the sodium dithionite in dry particulate form, e.g., powder, granules, or flakes, with the addition product stabilizer which is also in dry particulate form, e.g., powder, granules or flakes. The dry mixture can then be conveniently packaged, shipped, handled and used with little loss through spillage, vaporization or decomposition.

The relative proportions of stabilizer and reducing agent employed are not narrowly critical and can be varied over a wide range. For example, amounts of stabilizer which provide 001 to 2 or more, preferably 0.02 to l or more, mols of CRHSO M unit of the stabilizer per mol of sodium dithionite are advantageous. Greater amounts of stabilizer can be used, but apparently do not provide any commensurate further improvement.

The addition product stabilizers described herein are useful in any dyeing procedure using any vat or sulfur dyestuffs which are reduced by sodium dithionite under heated alkaline conditions. The particular dyeing process employed has no limiting effect on the use of the addition product stabilizer described and claimed herein, for example, these stabilizers can be used in machine dyeing processes for yarn in beams and packages. The stabilizers can also be used in the dyeing of fabric (knitted or woven) by the pad-steam process of the padjig process or any other process employed for dyeing fabrics,

yarns or fibrous rawstock, etc., with vat or sulfur dyestuffs which are reduced by sodium dithionite.

The term cellulosic textile" as used herein includes all-cotton fabrics and yarns, or fabrics and yarns containing cotton blended with synthetic or other fibers such as rayon, polyester, polyacrylonitrile fibers and the like and covers any yarn, rawstock of such fibers or any such fabric whether woven or knitted.

DESCRIPTION OF SPECIFIC EMBODIMENTS The following examples are presented wherein all parts and percentages are on a weight basis and all temperatures are on the Fahrenheit scale. The following terms used in the examples are explained as follows:

Igepon TA synthetic detergent formed by the condensation of oleyl chloride with methyl taurine. This detergent is stable to hot alkali, and is therefore suitable for vat dyeing operations.

BIOS-British Intelligence Objectives SubCommittee.

F.I.A.T.-United States Field Intelligence Agency Technical.

C.I.Color index number.

I-IEDTA-I-Iydroxyethyl ethylene diamine triacetic acid, usually used in the form of a trisodium salt. This compound functions merely as a water softening agent to prevent, for example, precipitation of vat dye by the calcium and magnesium salts present in the dyebath.

EXAMPLE 1 At F., an initial mixture was prepared comprising:

5 parts Anthraquinone Vat Golden Orange G (CL 1096) 1 part Igcpon T [0 parts sodium hydroxide (flakes) 984 parts water I000 parts To 500 parts of the above initial mixture at F. there was added 2.5 parts sodium dithionite (hydro) to produce vat dye solution A as a control.

To another 500-part portion of the initial mixture at 160 F. there was added, in accordance with this invention:

2.5 parts sodium dithionite and 5.0 parts of a solution containing:

10% by wt. of acetaldehyde 25% by wt. of sodium bisulfite 65% by wt. of water to produce vat dye solution B.

500 parts of vat solution A and 500 parts of vat solution B were each maintained at 160 F. without agitation in open dyepots for a period of 2 hours, during which time the reducing agent concentration in both solution A and solution B was measured at intervals listed below by usual titration methods and expressed in grams/liter sodium dithionite. The following data were obtained:

REDUCING AGENT CONCENTRATION (Grams Per Liter Sodium Dithionite) Solution .A" Solution B (Central) Time (min.)

This comparative data clearly shows the stabilizing action of the bisulfite addition products in accordance with this invention.

EXAMPLEZ Medium weight cotton fabric prepared for dyeing was padded continuously at ll F. with a pigment pad mixture comprising:

The impregnated fabric was dried at 225 F. and divided into four swatches, A, B, C," and D.

Swatch A was padded continuously at 80 F. through reducing solution No. l which comprised:

35.0 parts sodium hydroxide (flakes) [8.0 pans sodium dithionite 947.0 parts water l0O0.0 parts After being padded through reducing solution No. l, swatch A immediately was entered into a steamer and steamed 30 seconds at 2 l 5 F. The fabric was then finished off as usual.

Swatch 8" was padded continuously at 80 F. through reducing solution No. l but was exposed to air for 1 minute before being entered into the steamer for 30 seconds at 215 F. Swatch B" was then finished off in the same manner as swatch A.

Swatches A and 8" do not illustrate the present invention but are presented for comparison purposes.

Swatch C was padded continuously at 80 F. through reducing solution No. 2 which comprised:

350 parts sodium hydroxide (flakes) l8.0 parts sodium dithionite 27.0 parts of an aqueous solution containing:

10% by wt. acetaldehyde 25% by wt. sodium bisulfite 65% by wt. water 920.0 parts water l000.0 pans After being padded through reducing solution No. 2, swatch "C" immediately was entered into a steamer and steamed 30 seconds at 215 F. Swatch C" was finished off in the same manner as swatch A."

Swatch D was padded continuously at 80 F. through reducing solution No. 2, but was exposed to air for 1 minute be fore being entered into the steamer for 30 seconds at 215 F. Swatch D was then finished off in the same manner as swatch A.

Swatches C and D illustrate the present invention.

Examination of the four swatches revealed that:

Swatch A" was dyed a medium depth olive shade,

Swatch B was almost completely undyed,

Swatch C was dyed a medium depth olive shade, and

Swatch D" was dyed a medium depth olive shade.

These results clearly illustrate the stabilizing effectiveness of the addition product according to this invention.

EXAMPLE 3 Dyeing A" This part does not illustrate the invention but is presented for comparison purposes.

l,0l0 grams of cotton yarn in package form was placed in a commercial package dyeing machine at a liquor to goods ratio of 7.5-1. The yarn was wet out and rinsed in the usual manner, and

22.5 grams of sequestering agent of trisodium HEDTA 7.5 grams lgepon T 15.0 grams complex diaryl sulfonate dispersing agent were added to the dyebath which then was circulated through the packages for ten minutes at 160 F. Then percent of a dye mixture comprising:

121.2 grams Anthraquinone Vat Olive T (B.I.O.S.987, 7)

7.8 grams Anthraquinone Vat Dark Blue BO (CL 1099) was added to the dyebath and circulated through the packages for ten minutes at 160 F. Thereafter,

75.0 grams sodium hydroxide flakes (dissolved) and 30.0 grams sodium dithionite were added to the dyebath and dyeing was continued for 1 hour at 160 F.

The remaining 20 percent of the dye mixture was added and dyeing was continued for forty minutes. The yarn was finished off as usual.

Dyeing B This part illustrates the present invention. Dyeing B was conducted in exactly the same manner as dyeing A with the following exceptions:

1. In addition to the 75.0 grams sodium hydroxide and 30.0

grams sodium dithionite, there was added 4.5 grams of an aqueous solution containing:

10% by wt. acetaldehyde 25% by wt. sodium bisulfite 65% by wt. water 2. Dyeing was continued seventy minutes after the addition of the remaining 20 percent dye, and the yarn was finished off as usual.

During the course of both dyeing A and dyeing B, a record of reducing agent concentration expressed in grams/liter of sodium dithionite (Hydro) was made by the use of standard titration methods. Also, a record of redox potential was made by the use of a suitable instrument and standard technique. The following data were produced:

Dyeing u A i 1 g". Hydro Redox Potential Time (min.)

Z0 1.] l020 30 0.9 l025 40 0.7 l020 50 0.5 l0l5 60 0.4 l0l5 trace 910 [00 trace 890 DYEING B" g./l. Hydro Redox Potential final NaOH conc.

The above data clearly shows the stabilizing action of the bisulfite addition products in accordance with this invention.

EXAMPLE 4 At 80 R, an initial solution was prepared which comprised:

10 grams sodium hydroxide (flakes) 10 grams sodium dithionite (hydro) 3 grams trisodium HED'I'A 2 grams water I000 grams The initial solution is divided with minimum dyebath aeration into four 250 gram portions, A, B, C. and D, contained in four open dyepots.

Portion A was kept as a control.

To portion 8" was added 0.25 gram of thc anhydrous addition product fonned by the reaction of furfural with an aqueous solution of an equal molar amount of sodium bisulfitc, followed by dehydration of the product to produce the anhydrous addition product.

To portion C" was added 1.25 grams of the abovedescribed solid furfural-bisulfite addition product.

To portion D" was added 2.5 grams of the abovedescribed furfural-bisulfite addition product.

All four portions were heated to I60 F. and maintained at this temperature for l hour, during which time a record of reducing agent concentration expressed in grams/liter of sodium dithionite was made by the use of standard titration methods.

The following data were produced:

REDUCING AGENT CONCENTRATION (Grams Per Liter Hydro) A n c n Time (min) 5.7 u as 7.5

so 3.7 3.7 5.0 (H

These results illustrate the stabilizing effectiveness of the addition products and the increase of effectiveness with increasing amounts of the addition products in accordance with the present invention.

What is claimed is:

1. In the process of dyeing cellulosic textiles formed from a member selected from the class consisting of cotton and blends of cotton with synthetic fibers with vat dyes or sulfur dyes using sodium dithionite as the reducing agent, that improvement comprising using as a stabilizer for said reducing agent a compound of the formula wherein R is a monovalent radical selected from the class consisting of hydrogen and hydrocarbon having one to l8 carbon atoms, said stabilier being used in an amount providing about 0.01 to about 2 mols of l -Gll S 01M unit of said stabilizer per mol of said reducing agent.

2. Improvement as claimed in claim I wherein M is sodium.

3. Improvement as claimed in claim 2 wherein R is methyl. X is hydroxyl and n is l.

4. Improvement as claimed in claim 2 wherein R is furyl, X is hydroxyl and n is I. 

2. Improvement as claimed in claim 1 wherein M is sodium.
 3. Improvement as claimed in claim 2 wherein R is methyl, X is hydroxyl and n is
 1. 4. Improvement as claimed in claim 2 wherein R is furyl, X is hydroxyl and n is
 1. 